CN110603373B

CN110603373B - Method for controlling temperature of NOx control component and exhaust aftertreatment system

Info

Publication number: CN110603373B
Application number: CN201780090508.7A
Authority: CN
Inventors: 索兰·什万; 拉尔斯·卡尔汗玛尔; 弗雷德里克·布洛姆格伦
Original assignee: Volvo Truck Corp
Current assignee: Volvo Truck Corp
Priority date: 2017-06-02
Filing date: 2017-06-02
Publication date: 2022-04-12
Anticipated expiration: 2037-06-02
Also published as: CN110603373A; EP3631176B1; US11268415B2; EP3631176A1; US20200173325A1; WO2018219476A1

Abstract

The invention relates to a method for controlling the temperature of a NOx control component (10) in an exhaust aftertreatment system (1, 1') of an internal combustion engine (100). The NOx control component (10) has an inner surface portion (12) defining an inner component space (20) through which exhaust gas (3) is arranged to flow for NOx control and an outer surface portion (14) facing away from the inner component space (20). The method comprises the following steps: the temperature of at least a portion of the NOx control member (10) is controlled by a heat transfer medium (30, 30') disposed outside the outer surface portion (14).

Description

Method for controlling temperature of NOx control component and exhaust aftertreatment system

Technical Field

The invention relates to a method for controlling the temperature of a NOx control component in an exhaust aftertreatment system of an internal combustion engine. The invention also relates to an exhaust gas aftertreatment system comprising a NOx control component and a vehicle provided with such an exhaust gas aftertreatment system.

The invention may be applied to heavy vehicles such as trucks, buses and construction equipment. Although the invention will be described in relation to a truck, the invention is not limited to this particular vehicle, but may also be used in other vehicles, such as other heavy vehicles and automobiles.

Background

Vehicles, such as trucks and buses, are often equipped with exhaust aftertreatment systems (often referred to simply as EATS) downstream of the engine and are configured to reduce emissions resulting from engine exhaust. The EATS may include different types of components to reduce different types of emissions, and is generally related to the type of engine used in the vehicle. For example, EATS coupled to diesel engines typically include NOx control components to control NOx. NOx may be controlled in various ways, such as by controlling NO₂The ratio of/NOx in, for example, a Diesel Oxidation Catalyst (DOC) component. The DOC component typically includes a catalyst material, such as palladium, platinum, and/or alumina, all of which are used to oxidize nitrogen constituents (e.g., NOx) to form at least NO₂And oxidizing the hydrocarbons and carbon monoxide to form carbon dioxide and water. In another example, the EATS may include components that at least temporarily adsorb or store nitrogen-based emissions (e.g., NOx emissions) in a so-called NOx adsorber or NOx trap. Further, nitrogen-based emissions may be treated in a Selective Catalytic Reduction (SCR) component, where NOx is reduced to nitrogen using a reagent such as ammonia. Ammonia is typically supplied to the EATS by injecting urea into the exhaust gas, which then undergoes thermal decomposition and hydrolysis to ammonia. EATS also typically include a filter (e.g., a particulate filter) for reducing soot in the exhaust. The cleaned, or at least reduced, exhaust then exits the EATS and the vehicle through the vehicle's exhaust duct.

Government regulations impose strict limits on vehicle emissions, for example, upcoming emission regulations, such as CARB Ultra Low NOx (CARB Ultra Low NOx), are planned to be effective around 2024 and 2025 years. This, together with the continuing need to increase vehicle fuel economy, means that more efficient and durable EATS are needed. One mode of operation that is to be improved with respect to emissions is cold start of the engine (i.e., operation of the engine and the EATS before the operating temperature of the components is reached).

US2015/0377102 addresses NOx emissions from vehicles and solves the problem of these emissions during cold starts. According to the abstract, US2015/0377102 discloses: an internal combustion engine system includes an engine and an aftertreatment system connected to the engine to receive an exhaust gas flow from the engine. The aftertreatment system includes: a passive storage device for passively storing NOx and/or hydrocarbons produced by the engine during cold start and low temperature operating conditions; and a NOx reduction catalyst downstream of the passive storage device for receiving NOx released from the passive storage device when a temperature condition in the exhaust stream and/or a temperature of the NOx reduction catalyst is above an effective temperature for NOx reduction. The diagnostics of the passive storage device and/or the sensor downstream of the passive storage device are based at least in part on an expected sensor output responsive to a storage mode of operation or a release mode of operation of the passive storage device. Further, reductant injection control is provided in response to the amount of NOx released from the passive storage device.

However, the system in US2015/0377102 is relatively complex, and there is a need in the industry for a simpler but effective system to treat vehicle emissions.

Disclosure of Invention

In view of the above-mentioned and other drawbacks of the prior art, it is an object of the present invention to provide an improved control of the temperature of a NOx control component in an exhaust aftertreatment system.

According to a first aspect of the invention, the object is achieved by a method for controlling the temperature of a NOx control component in an exhaust aftertreatment system of an internal combustion engine. The NOx control component has an inner surface portion defining an inner component space through which exhaust gas is arranged to flow for NOx control and an outer surface portion facing away from the inner component space. The method comprises the following steps:

controlling a temperature of at least a portion of the NOx control component via a heat transfer medium disposed outside of the outer surface portion.

By providing for the heat transfer medium to be arranged outside the outer surface portion of the NOx control component, an efficient way of controlling the temperature of at least a part of the NOx control component is provided. In addition, by arranging the heat transfer medium outside the outer surface portion of the NOx control component, temperature control of the exhaust aftertreatment system is allowed without, for example, directly mixing the exhaust gas with hot or cold gas, and thus, components in the EATS downstream of the NOx control component may remain relatively unaffected.

It should be understood that the term "controlling" the temperature of at least a portion of the NOx control component includes heating and/or cooling of at least a portion of the NOx control component. Thus, it should be understood that the method according to the present invention may include cooling and heating the NOx control component via the outer surface portion. The choice of heating and/or cooling depends on, for example, the operating mode of the vehicle and, for example, the type and operating mode of the NOx control component. For example, for at least one mode of operation (e.g., a cold start of the engine), and for a NOx control component that functions as a NOx trap or NOx adsorber, to delay release of any emissions adsorbed by the NOx control component, the NOx control component may be subjected to cooling until an operating temperature of other components in the EATS is reached (e.g., until an operating temperature of an SCR component in the EATS is reached). According to another example, for at least one other operating mode, the NOx control component is heated to increase NO₂the/NOx ratio.

It should be noted that sensors, control units, diagnostic methods etc. known in the art and described e.g. in US2015/0377102 are typically used to determine the operation mode and whether the NOx control component should be subjected to heating or cooling. For example, EATS includes a sensor configured to detect and measure NO, NOx, CO₂Other hydrocarbons and/or O₂At least one sensor of quantity. Further, the EATS may include at least one control unit connected to the at least one sensor, and the at least one control unit is configured to analyze and diagnose an emission condition and/or an operating mode of the vehicle. Further, the control unit may be connected to a valve (e.g., a shut-off valve) or other component in the EATS to control heating and/or cooling of the NOx control component.

It should be understood that the outer surface portion of the NOx control member may be referred to as a jacket of the NOx control member. Further, it should be understood that when it is stated that "at least a portion of said NOx control component" is temperature controlled, the heat transfer medium is in thermal contact with the outer surface portion along at least a portion of the length of the NOx control component. Therefore, the interior component space closest to the outer surface portion to be subjected to the heat transfer medium is usually subjected to most of the temperature control. According to one embodiment, the method comprises the step of controlling the temperature of the NOx control member (e.g. the whole NOx control member) by means of a heat transfer medium arranged outside the outer surface part. For example, the heat transfer medium may be arranged in thermal contact with the outer surface portion along the entire length of the NOx control component.

According to an embodiment, heat is received from or released to an inner component space of the NOx control component, for example, via the outer surface portion (e.g. the outer surface portion is comprised in an outer wall of the NOx control component). Thus, for at least a portion of the heat transfer, heat is conducted through at least a portion of the NOx control component, such as through external wall heat conduction.

It should be understood that the heat transfer medium is arranged to release heat to (heat up) or receive heat from (cool down) the NOx control component. Thus, the NOx control component (e.g., the internal component space) is heated or cooled by the heat transfer medium.

According to one embodiment, the NOx control component is a Diesel Oxidation Catalyst (DOC) component or a NOx adsorber, such as a Passive NOx Adsorber (PNA), a Lean NOx Trap (LNT), or other type of NOx adsorber.

Thus, the NOx control component, often referred to as an EATS component, controls NOx in some manner, for example, by at least temporarily adsorbing or storing NOx and/or by oxidizing NOx to form at least NO₂. Thus, and in accordance with one embodiment, the term "for NOx control" means that the NOx control means controls NOx at least by temporarily adsorbing NOx, storing NOx, and/or oxidizing NOx. According to one embodiment, the DOC component comprises a catalyst adapted to adsorb or store NOxAnd thus the NOx control component may be referred to as a DOC having a NOx adsorption capacity.

According to one embodiment, the step of controlling the temperature comprises directing a flow of the heat transfer medium through the outer surface portion of the NOx control component.

Thus, the heat transfer medium may transfer heat to the outer surface portion by at least partial convective heat transfer, thereby providing an efficient heat transfer process between the heat transfer medium and the NOx control component. It should be noted that the heat transfer medium may flow only over a part of said outer surface portion of the NOx control member, e.g. up to 50% or 70% or 90% of the outer surface portion. According to one embodiment, the heat transfer medium is arranged to flow on the outer surface portion along the entire periphery of the NOx control member.

According to one embodiment, said step of controlling the temperature comprises cooling at least a part of said NOx control component by said heat transfer medium.

That is, the heat transfer medium receives heat from the outer surface portion of the NOx control member, and thus cools the NOx control member. For example, the heat transfer medium may receive heat as it flows over the outer surface portion of the NOx control component. This step may be used, for example, when delayed release of a substance adsorbed or stored by a NOx control component (e.g., a NOx adsorber) is desired, and the adsorbed or stored substance should be released when other components in the EATS reach operating temperatures.

According to one embodiment, the method comprises the further steps of: draining (discharging) a sub-portion of the exhaust gas downstream of the NOx control component and forming at least a portion of the heat transfer medium using the sub-portion.

Thus, a relatively simple arrangement for providing at least a part of the heat transfer medium is provided. It should be appreciated that downstream of the NOx control component, the exhaust gas is typically cooler than upstream of the NOx control component due to heat dissipation from the exhaust gas to the ambient environment and heat release to other components in the EATS, such as a Selective Catalytic Reduction (SCR) component. Thus, by draining a sub-portion of the exhaust gas downstream of the NOx control component, a relatively cool gas flow is provided which can be used to receive heat from the NOx control component. Thus, it should be appreciated that the sub-portion of the exhaust gas that is discharged downstream of the NOx control component serves to form at least a portion of the heat transfer medium flowing over the outer surface portion of the NOx control component. A sub-portion of the exhaust gas may be discharged downstream of the SCR component in the EATS.

According to one embodiment, the method comprises the further step of using an external cooling gas (e.g. ambient air) to form at least part of said heat transfer medium.

Thus, an efficient but relatively inexpensive way of providing at least part of the heat transfer means is provided. It is to be understood that the external cooling gas is used to form at least a part of the heat transfer medium flowing on the outer surface portion of the NOx control member. The external cooling gas may be mixed, for example, with the sub-portion being discharged downstream of the NOx control component before being subjected to heat transfer with the outer surface portion of the NOx control component.

The external cooling gas may be used, for example, as an enhancement of cooling during cold engine start-up and/or as cooling during normal operation when the EATS is hot.

According to one embodiment, said step of controlling the temperature comprises heating at least a part of said NOx control component by said heat transfer medium.

That is, the heat transfer medium releases heat to the outer surface portion of the NOx control member and thus heats the NOx control member. For example, the heat transfer medium may release heat as it flows over the outer surface portion of the NOx control component.

According to one embodiment, the EATS comprises means for heating and cooling at least a portion of the NOx control component by a heat transfer medium arranged outside the outer surface portion. That is, the device is configured to sequentially or simultaneously heat and cool at least a portion of the NOx control component by a heat transfer medium disposed outside the outer surface portion. For example, in certain operating modes (e.g., during a cold start of the engine), it may be desirable to cool the NOx control component to delay release of any substances adsorbed or stored in the NOx control component, while during other operating modes when the NO/NOx ratio should be increased, it may be desirable to heat the NOx control component. For example, if the NOx control component is a lean NOx trap LNT, a rapid increase in temperature is desired, which may be performed by initial heating of the LNT. After the LNT reaches the desired temperature, i.e., its operating temperature, it is desirable to maintain that temperature, which may be performed, for example, by subsequently cooling the LNT to remove any excess heat.

According to one embodiment, the method comprises the further steps of: heating a fluid in a heating line by a burner and forming at least a portion of the heat transfer medium using the heated fluid.

That is, the heating line includes a heating fluid heated by a burner, the heating fluid being fluidly connected to the outer surface portion of the NOx control component. Thus, an efficient but relatively inexpensive way of providing at least part of the heat transfer means is provided. It should be understood that the heating fluid is used to form at least a part of the heat transfer medium flowing on the outer surface portion of the NOx control member.

According to one embodiment, the heat upstream of the NOx control component is used as at least part of the heat transfer medium by heat exchange or by direct mixing via a sub-part of the exhaust flow of the exhaust gas.

According to one embodiment, wherein the step of controlling the temperature comprises receiving heat from or releasing heat to the NOx control component by a phase change of the heat transfer medium.

Thus, an alternative way of flowing the heat transfer medium over the outer surface portion of the NOx control component is provided. Therefore, the heat transfer medium has been selected to be a phase change heat transfer medium, i.e., a heat transfer medium of: which is adapted to the temperature range of the NOx control means and to the desired temperature variation of the NOx control means.

For example, by cooling the NOx control component in a phase change, the heat transfer medium will keep the NOx control component at a low temperature as long as the heat transfer medium has the ability to absorb heat. This may delay heating of the NOx control component, for example, when the EATS system to its operating temperature.

According to one embodiment, the method comprises the further steps of: the NOx control component is heated by adding heat to the exhaust gas upstream of the NOx control component.

Therefore, the process of controlling the NOx control member by the heat transfer medium arranged outside the outer surface portion of the NOx control member can be combined with the following process: heat is added to the exhaust gas by a heat exchanger, turbine bypass, and/or mixing heated gases with the exhaust gas upstream of the NOx control component. Thus, the temperature of the NOx control component can be controlled in different ways.

In the following sections, more detailed examples of the NOx control means will be described.

For example, the NOx control component may be a Passive NOx Adsorber (PNA), possibly with the functionality of a DOC. PNAs may adsorb or store incoming NOx when the temperature is relatively low (i.e., relatively cold), and release stored NOx when the temperature rises above a threshold temperature (typically about 180 ℃). The use of PNA in exhaust aftertreatment systems may be more effective if stored NOx is released from PNA when the downstream SCR component reaches its operating temperature. A problem with using PNA in EATS before is that when the PNA exceeds a threshold temperature, the SCR component has not yet reached its operating temperature and therefore is too cold to treat the incoming NOx. However, by controlling the temperature of the PNA by disposing a heat transfer medium outside the outer surface portion of the PNA, the release of stored NOx can be effectively delayed until the SCR component reaches its operating temperature, and thus NOx can be effectively treated.

For embodiments in which the NOx control component is an oxidation catalyst component (e.g., DOC), NO from the DOC₂the/NOx ratio is preferably controlled such that: when it reaches the SCR component, it is about 0.5 (this is due to the so-called desired rapid SCR reaction). NO₂the/NOx ratio depends on the temperature and is therefore determined by the temperature known to the person skilled in the artAnd (5) controlling. If possible, NO₂Keeping the/NOx ratio at 0.5, an iron based catalyst (e.g. iron exchanged zeolite) in the SCR component can be used, which has a high activity during fast SCR reactions compared to other SCR catalysts. Thus, the size of the SCR component can be reduced for the same efficiency. In addition, control of NO₂the/NOx ratio may further improve passive soot regeneration in filters (e.g., diesel particulate filters, DPF), where high NO₂The concentration is preferred.

Thus, it should be appreciated that cooling the NOx control component may help improve the efficiency of the EATS by reducing NOx emissions. For example, during a cold start of the engine, cooling of the NOx control component (e.g., PNA) helps prevent desorption or release of NOx when the SCR assembly has not reached its operating temperature. In addition, in NO₂Where the/NOx ratio is greater than 0.5 (which typically occurs when the DOC is new or unused and the temperature of the DOC is greater than 250 ℃), cooling of the DOC may cause NO to be emitted₂the/NOx ratio returns to about 0.5.

Heating of NOx control components (e.g., DOC or PNA) can be used to increase NO₂the/NOx ratio, and therefore, the efficiency of the EATS is increased by ensuring that as much NOx as possible is converted by the rapid reaction in the SCR. When the catalyst (e.g., present in the DOC or combination of DOC and PNA) is new or unused, heating achieves a method by which the operating temperature of the NOx control component can be quickly reached or maintained, and thus the NO is made available₂the/NOx ratio reaches 0.5. This may be useful after an idle period (e.g., after the DOC has cooled below its optimum temperature but the temperature of the SCR component is above its operating temperature). For aged DOCs, heating may be one way to compensate for deactivation, which typically requires lower NO₂the/NOx ratio.

According to a second aspect of the invention, the object is achieved by an exhaust gas aftertreatment system comprising a NOx control component. The NOx control component comprises an inner surface portion defining an inner component space through which exhaust gas is arranged to flow for NOx control and an outer surface portion facing away from the inner component space, wherein the exhaust aftertreatment system further comprises a heat transfer device arranged to at least partially surround the NOx control component, the heat transfer device being configured to contain a heat transfer medium for controlling a temperature of the NOx control component by receiving heat from or releasing heat to the outer surface portion of the NOx control component.

The effects and features of the second aspect of the present invention are largely analogous to those described above in connection with the first aspect of the inventive concept. The embodiments mentioned in relation to the first aspect of the invention are largely compatible with the second aspect of the invention, some of which are explicitly disclosed below.

According to one embodiment, the heat transfer device comprises an inlet for receiving the heat transfer medium, and an outlet for discharging the heat transfer medium, thereby allowing the heat transfer medium to flow through the heat transfer device, and wherein the heat transfer device is configured to direct the flow of the heat transfer medium over the outer surface portion so as to receive heat from or release heat to the NOx control component.

Such a heat transfer device may be referred to as a flow heat transfer device because it provides the function of allowing the heat transfer medium to flow through the heat transfer device and thus through the outer surface portion of the NOx control component. Thus, the inlet may be in fluid connection with any type of cooling device and/or in fluid connection with any type of heating device. The outlet may be in fluid connection with an exhaust pipe of a vehicle, for example.

According to one embodiment, the exhaust aftertreatment system further comprises a selective catalytic reduction unit arranged downstream of the NOx control component, and a cooling bypass channel configured to drain a sub-portion of the exhaust gas downstream of the catalytic reduction unit, and wherein the heat transfer medium at least partially comprises the sub-portion to receive heat from the NOx control component.

Thus, an efficient but relatively inexpensive way of providing at least part of the heat transfer means is provided. The cooling bypass passage is fluidly connected with an inlet of a heat transfer device, thereby enabling a sub-portion of the exhaust gas to flow into the heat transfer device via the inlet, over the outer surface portion of the NOx control component and to the outlet.

According to one embodiment, the exhaust aftertreatment system further comprises an air inlet configured to receive ambient air, and wherein the heat transfer medium at least partially comprises the received ambient air to receive heat from the NOx control component.

Thus, an efficient but relatively inexpensive way of providing at least part of the heat transfer means is provided. It should be appreciated that another cooling gas other than ambient air may enter through the air inlet. The inlet port is in fluid connection with an inlet of the heat transfer device, thereby enabling ambient air or another external cooling gas to flow into the heat transfer device via said inlet port, over said outer surface portion of said NOx control component and to said outlet port. Ambient air or another external cooling gas may be mixed with the sub-portion of the exhaust gas being discharged downstream of the NOx control component, e.g. before being subjected to heat transfer with the outer surface portion of the NOx control component.

According to one embodiment, the exhaust gas aftertreatment system further comprises a burner configured to heat fluid in a heating line, and wherein the heat transfer medium is at least partially constituted by the heated fluid, so as to release heat to the NOx control component.

Additionally or alternatively, the heating line may exchange heat with the exhaust gas stream upstream of the NOx control component via a heat exchanger, instead of or in addition to using a burner for heating purposes.

That is, the heating fluid is in fluid connection with the inlet of the heat transfer device and thus with the outer surface portion of the NOx control component. Thus, an efficient but relatively inexpensive way of providing at least part of the heat transfer means is provided.

According to one embodiment, the EATS comprises means for heating and cooling at least a portion of the NOx control component by means of a heat transfer medium arranged outside the outer surface portion in the heat transfer means. That is, the device is configured to sequentially or simultaneously heat and cool at least a portion of the NOx control component by a heat transfer medium disposed outside the outer surface portion. The choice of heating and/or cooling depends on, for example, the operating mode of the vehicle and, for example, the type and operating mode of the NOx control component. For clarity, the cooling bypass passage and subparts may be referred to as a first cooling device of the NOx control component, the intake and ambient air may be referred to as a second cooling device of the NOx control component, the burner and the heating line may be referred to as a first heating device of the NOx control component, and the heat exchanger and the heating line may be referred to as a second heating device of the NOx control component.

According to one embodiment, the heat transfer medium is selected to be a phase-change heat transfer medium, and wherein the heat transfer device comprises an expansion vessel configured to: the expansion vessel compensates for volume changes of the phase-change heat transfer medium when the phase-change heat transfer medium undergoes a phase change upon receiving heat from or releasing heat to the NOx control component.

Thus, an alternative way of flowing the heat transfer medium over the outer surface portion of the NOx control component is provided. Therefore, the heat transfer medium has been selected to be a phase change heat transfer medium, i.e. a heat transfer medium that is adapted to the temperature range of the NOx control component and to the desired temperature variation of the NOx control component. To this end, the expansion vessel is dimensioned to correspond to the selected phase-change heat transfer medium. For example, when cooling the outer surface portion of the NOx control component, the phase-change heat transfer medium is selected such that it undergoes a phase change from solid to liquid or from liquid to gas to achieve the desired temperature change of the oxidation catalyst. The expansion vessel is thus used to compensate for volume changes of the phase change heat transfer medium when changing from a solid to a liquid or from a liquid to a gas, for example. Correspondingly, in order to heat the outer surface portion of the NOx control member, the phase-change heat transfer medium is selected such that it undergoes a phase change, for example, from liquid to solid or from gas to liquid, to achieve a desired change in temperature of the oxidation catalyst. Thus, the expansion vessel serves to compensate for the volume change of the phase-change heat transfer medium when changing from a liquid to a solid or from a gas to a liquid. Such volume expansion or reduction characteristics with respect to phase change, and the desired need for cooling or heating, depend on the choice of phase change thermal transfer medium and are known to those skilled in the art. Thus, the expansion vessel is generally adapted to the choice of phase-change heat transfer medium.

According to one embodiment, the NOx control component is a Diesel Oxidation Catalyst (DOC) component or a NOx adsorber, e.g. a Passive NOx Adsorber (PNA), a Lean NOx Trap (LNT) or another type of NOx adsorber, as described in relation to the first aspect of the invention.

According to a third aspect of the invention, the object is achieved by a vehicle comprising an exhaust aftertreatment system according to the second aspect of the invention.

Other advantages and advantageous features of the invention are disclosed in the following description.

Drawings

The above and other objects, features and advantages of the present invention will be better understood from the following illustrative and non-limiting detailed description of exemplary embodiments thereof, in which:

FIG. 1 is a side view of a vehicle including an exhaust aftertreatment system and an internal combustion engine according to one example of the invention;

FIG. 2 is a schematic illustration of an exhaust aftertreatment system according to an example of the invention;

FIG. 3 illustrates a cross-sectional view of a NOx control component and a heat transfer device included in an exhaust aftertreatment system, according to an embodiment of the invention;

FIG. 4 illustrates a cross-sectional view of a NOx control component and a heat transfer device included in an exhaust aftertreatment system, according to an alternative embodiment of the present invention;

FIG. 5 is a schematic illustration of an exhaust aftertreatment system according to an example of the invention;

FIG. 6 is a flowchart illustrating steps of a method for controlling the temperature of a NOx control component in accordance with one embodiment of the present invention.

Detailed Description

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, the embodiments are provided for sufficiency and completeness. Like reference numerals refer to like elements throughout the specification.

With particular reference to FIG. 1, a vehicle 800 is provided that includes an exhaust aftertreatment system (EATS)1, 1 ' according to one example of the invention, and a combustion engine 100, such as an internal combustion engine 100, disposed upstream of the EATS 1,1 ' and fluidly connected to the EATS 1,1 ' via a conduit 802. The vehicle 800 depicted in fig. 1 is a truck 800, to which truck 800 the inventive concept, which will be described in detail below, is adapted.

FIG. 2 shows a schematic diagram of an EATS 1 according to one embodiment of the invention. In the non-limiting example of FIG. 2, the EATS 1 includes various components, such as a NOx control component 10, a filter 20 (e.g., a particulate filter for reducing the soot content of the exhaust 3), and a Selective Catalytic Reduction (SCR) component 60. Further, the EATS 1 includes: a cooling bypass channel 5 ' with a corresponding shut-off valve 6 ', which cooling bypass channel 5 ' is configured to drain a sub-portion 5 of the exhaust gas 3 downstream of the SCR component 60; and an air inlet 40 ' with a corresponding shut-off valve 41 ', the air inlet 40 ' being configured to receive ambient air 40. Both the cooling bypass passage 5 'and the air inlet 40' are fluidly connected to a jacket or an outer surface portion of the NOx control member 10, which will be described later. Further, in fig. 2, an optional burner 70 and an optional heating line 72 are fluidly connected to a jacket or outer surface portion of the NOx control component 10, which will be described below.

Turning to FIG. 3, a schematic diagram of the NOx control component 10 and the fluid heat transfer device 50 of FIG. 2 is shown. The NOx control component 10 comprises an inner surface portion 12 defining an inner component space 20 through which the exhaust gas 3 is arranged to flow for NOx control. The NOx control member 10 further comprises an outer surface portion 14 facing away from said inner member space 20. The fluid heat transfer device 50 is arranged to at least partially surround the NOx control component 10, and in fig. 3 the fluid heat transfer device 50 completely surrounds the NOx control component 10. The fluid heat transfer device 50 is configured to contain a heat transfer medium 30, which heat transfer medium 30 may receive heat from or release heat to the outer surface portion 14 of the NOx control component 10 in order to at least partially control the temperature of the NOx control component 10.

In more detail, as shown in fig. 3, the fluid heat transfer device 50 includes a heat transfer housing 51, wherein the heat transfer housing 51 defines a heat transfer space 53 containing the NOx control component 10 and containing the heat transfer medium 30. Therefore, in the heat transfer space 53, heat transfer is allowed to occur between the outer surface portion 14 of the NOx control member 10 and the heat transfer medium 30.

As also shown in the embodiment of FIG. 3, fluid heat transfer device 50 includes an inlet 52 for receiving heat transfer medium 30 and an outlet 54 for discharging heat transfer medium 30. Thereby, the heat transfer medium 30 is allowed to flow through the fluid heat transfer device 50 and the heat transfer space 53 so as to exchange heat with the outer surface portion 14 of the NOx control member 10 (indicated by arrows in fig. 3). To this end, inlet 52 is preferably arranged to direct a flow of heat transfer medium 30 over outer surface portion 14. According to one embodiment, as shown in fig. 3, the inlet 52 is arranged to direct the fluid of the heat transfer medium 30 to the inlet portion of the NOx control component 10. Therefore, effective heat transfer of the NOx control component 10 can be achieved. It should be noted, however, that inlet 52 may be disposed at different locations along the length of the NOx control component and/or more than one inlet (not shown) may be disposed in fluid heat transfer device 50.

The function of EATS 1 will now be described in more detail with reference to fig. 2 and 3. Exhaust 3 or exhaust stream 3 from engine 100 (shown in FIG. 1) is supplied to EATS 1 through conduit 802, which is fluidly connected to NOx control component 10. The exhaust gas flow 3 then passes through the EATS 1, i.e., through the internal component space 20 of the NOx control component 10, and then through other components (e.g., the filter 20 and the SCR component 60) to be cleaned before exiting the EATS 1 via the exhaust pipe 803. The EATS 1 in fig. 2 is configured to effect cooling of the NOx control component 10 in at least one exemplary mode of operation by using a sub-portion 5 of the cooling bypass passage 5 'and/or using ambient air 40 received by the air intake 40'. It should be understood that either or both of the cooling bypass channel 5 'and the air inlet 40' may be shut off by the respective shut-off valve 6 ', 41' in order to control, or even stop, the cooling of the NOx control component 10. In the example shown in fig. 2, the sub-portion 5 of the exhaust gas and the ambient air 40 are combined into a cooling flow 42, which cooling flow 42 is supplied to an inlet 52 of a fluid heat transfer device 50, thereby allowing it to flow over the outer surface portion 14 of the NOx control component 10 in order to absorb heat and thus cool the NOx control component 10. That is, EATS 1 in FIG. 2 is configured to utilize cooling stream 42 as heat transfer medium 30. Thus, the heat transfer medium in the embodiment shown in fig. 2 comprises at least partly the sub-section 5 and at least partly the ambient air 40 for receiving heat from the NOx control component 10.

Additionally or alternatively, the EATS 1 in fig. 2 is configured to heat the NOx control component 10. Therefore, for such an embodiment, it is preferable to close the shut valve 6 ' of the cooling bypass passage 5 ' and the shut valve 41 ' of the intake port 40, respectively. The EATS 1 includes a burner 70, the burner 70 configured to heat fluid in the heating line 72, whereby the heated fluid is used to form at least a portion of the heat transfer medium 30. Thus, the heated fluid in the heating line 72 is directed to the inlet 52 of the fluid heat transfer device 50 and allowed to flow over the outer surface portion 14 of the NOx control component 10 to release heat to the NOx control component 10. Additionally or alternatively, the heating line 72 may exchange heat with the exhaust gas flow 3 upstream of the NOx control component 10 via a heat exchanger 70', instead of or in addition to using the burner 70 for heating purposes.

It should be noted that all or only some (e.g., only one) of the heating and cooling means described with respect to fig. 2 may be included in the EATS 1. For the sake of clarity, the cooling bypass channel 5 ' and the subsection 5 may be referred to as a first cooling means of the NOx control part 10, the air inlet 40 ' and the ambient air 40 may be referred to as a second cooling means of the NOx control part 10, the burner 70 and the heating line 72 may be referred to as a first heating means of the NOx control part 10, and the heat exchanger 70 ' and the heating line 72 may be referred to as a second heating means of the NOx control part 10. For example, the cooling bypass passage 5 'may be omitted (or closed by the shut-off valve 6'), and only the intake port 40 may be used to cool the outer surface portion 14 of the NOx control member 10. Correspondingly, the intake port 40 ' may be omitted (or closed by the shut-off valve 41 '), and only the cooling bypass passage 5 ' may be used to cool the outer surface portion 14 of the NOx control member 10. Also, the burner 70 and/or heat exchanger 70' may be omitted from the EATS or they may be used separately and shut down individually as required by the NOx control component 10.

Turning to fig. 4, a schematic diagram of the NOx control component 10 of fig. 2 and 3, and the expansion heat transfer device 50' is shown. The NOx control portion 10 in fig. 4 is the same as the NOx control portion described with reference to fig. 3, and features will not be described here, but the same reference numerals are used for corresponding features. The expansion heat transfer device 50' is arranged to at least partially surround the NOx control component 10, and in fig. 4, the expansion heat transfer device 50 completely surrounds the NOx control component 10. The expansion heat transfer device 50 ' is configured to contain a heat transfer medium 30 ', which heat transfer medium 30 ' can receive heat from the outer surface portion 14 of the NOx control component 10 or release heat to the outer surface portion 14 of the NOx control component 10 in order to at least partially control the temperature of the NOx control component 10.

In more detail, and as shown in fig. 4, the expansion heat transfer device 50 ' includes a heat transfer housing 51 ', wherein the heat transfer housing 51 ' defines a heat transfer space 53 ' housing the NOx control component 10 and containing the heat transfer medium 30 '. The heat transfer medium 30 'comprised is selected as the phase change heat transfer medium 30', which means that: the characteristics of the heat transfer medium 30 'are selected such that the heat transfer medium 30' will undergo a phase change when receiving heat from the outer surface portion 14 of the NOx control component 10 or releasing heat to the outer surface portion 14 of the NOx control component 10. Therefore, the phase change heat transfer medium 30' is adapted to the temperature range of the NOx control component 10 and the desired temperature change of the NOx control component 10. Therefore, in the heat transfer space 53 ', heat transfer is allowed between the outer surface portion 14 of the NOx control member 10 and the phase-change heat transfer medium 30'.

As also shown in the embodiment in fig. 4, the expansion heat transfer device 50 ' includes an expansion vessel 56 ', the expansion vessel 56 ' being configured to: the expansion vessel 56 ' compensates for the change in volume of the phase change heat transfer medium 30 ' as the phase change heat transfer medium 30 ' undergoes a phase change by receiving heat from the NOx control component 10 or releasing heat to the NOx control component 10. To this end, the expansion vessel 56 'is sized to correspond to the selected phase-change heat transfer medium 30'.

The function of the expanding heat transfer device 50' will now be described in more detail. In order to cool the outer surface portion 14 of the NOx control component 10, the phase-change heat transfer medium 30' is selected such that it undergoes a phase change from solid to liquid or from liquid to gas to achieve the desired temperature change of the oxidation catalyst. Thus, expansion vessel 56' serves to compensate for the change in volume of the phase change heat transfer medium when changing from a solid to a liquid or from a liquid to a gas, for example. Correspondingly, in order to heat the outer surface portion 14 of the NOx control member 10, the phase-change heat transfer medium is selected such that it undergoes a phase change, for example, from liquid to solid or from gas to liquid, to achieve a desired change in temperature of the oxidation catalyst. Thus, expansion vessel 56' serves to compensate for the change in volume of the phase-change heat transfer medium as it changes from liquid to solid or from gas to liquid. Such volume expansion or reduction characteristics with respect to phase change, and the desired need for cooling or heating, depend on the choice of phase change thermal transfer medium 30' and are known to those skilled in the art. Accordingly, expansion vessel 56 'is generally suitable for selection of phase change heat transfer medium 30'.

Fig. 5 shows an EATS 1' similar to EATS 1 of fig. 2, so the same reference numerals are used for corresponding features and fig. 5 will not be described again in detail. Furthermore, the function of the EATS 1 'is similar to that of the EATS 1 of fig. 2, particularly with respect to the flow of exhaust gas 3 through the EATS 1', and therefore will not be described in detail. However, the EATS 1 'of fig. 5 includes the expansion heat transfer device 50' described with reference to fig. 4, rather than the fluid heat transfer device 50 described with reference to fig. 3. Therefore, as described with reference to fig. 4, according to the selection of the phase-change heat transfer medium 30 ', the outer surface portion 14 of the NOx control member 10 can be heated and cooled using the expansion heat transfer device 50', and thus the cooling bypass passage 5 ', the intake port 40', and the heating line 72 can be omitted.

As shown in fig. 5, the EATS 1' includes an optional exhaust gas combustor 80 and a turbine unit 90 disposed upstream of the NOx control component 10. The exhaust gas burner 80 may be used to heat the exhaust gas 3 before the exhaust gas 3 enters the NOx control component 10 and/or to heat the exhaust gas after the NOx control component 10, and the turbine unit 90 may be provided with a turbine bypass passage 92 so that the hot exhaust gas bypasses the turbine unit 90 and thus heats the exhaust gas 3 before the exhaust gas 3 enters the NOx control component 10.

As also shown in fig. 5, the EATS 1' includes an optional cooling line 94, e.g., supplied with ambient air, the cooling line 94 being configured to directly cool the exhaust gas 3 prior to the NOx control component 10. Thus, the cooling line 94 may be used to cool the exhaust gas 3 before the exhaust gas 3 enters the NOx control component 10.

The exhaust gas heating and/or cooling arrangements shown in FIG. 5 (i.e., the combustor 80, and/or the turbine unit 90 having the turbine bypass passage 92, and/or the cooling line 94 shown in FIG. 5) are also applicable to the EATS 1 of FIG. 2.

The invention will now be described with reference to a method for controlling the temperature of a NOx control component 10 in an exhaust aftertreatment system EATS 1, 1' as described in fig. 2 and 5. The method is described in the flowchart of fig. 6, and the reference numerals used in fig. 1 to 5 will be used throughout the description of the flowchart of fig. 6 when referring to the corresponding features.

In a first step 601 of the method, the temperature of at least a part of the NOx control member 10 is controlled by means of a heat transfer medium 30, 30' arranged outside the outer surface portion 14 of the NOx control member 10. Thus, the heat transfer medium 30, 30' is arranged to release heat to the NOx control component 10 or to receive heat from the NOx control component 10 via the outer surface portion 14.

In a second step 603, the first step 601 of controlling the temperature comprises cooling at least a part of the NOx control component 10 by the heat transfer medium 30, 30'. That is, the second step 603 includes cooling at least a portion of the NOx control component 10 by receiving heat from the outer surface portion 14.

In the following, various alternative steps relating to the use of the fluid heat transfer device 50 or the use of the expansion heat transfer device 50' are described. In more detail, the first and third alternative steps relate to the use of a fluid heat transfer device 50, while the second and fourth alternative steps relate to the use of an expansion heat transfer device 50'.

In a first alternative first step 603a1, the second step 603 of cooling comprises directing a flow 40 of heat transfer medium 30 to flow over an outer surface portion of the NOx control component 10. Therefore, when the heat transfer medium 30 flows over the outer surface portion 14, the heat transfer medium 30 can receive heat from the NOx control member 10.

In a first alternative second step 603a2, a sub-portion 5 of the exhaust gas downstream of the NOx control component 10 is discharged and used to form at least a part of the heat transfer medium 30.

In a first alternative third step 603a3, the first alternative second step 603a2 may be supplemented or, instead of the first alternative second step 603a2, an external cooling gas (e.g., ambient air 40) may be used to form at least a portion of the heat transfer medium 30.

In a second alternative first step 603b1, the second step 603 of cooling comprises receiving heat from the NOx control component 10 by a phase change of the heat transfer medium 30'. This step 603b1 is generally preceded by the step of selecting a heat transfer medium that is selected to be a phase-change heat transfer medium that is suitable for the desired temperature change of the NOx control component 10.

In a third step 605, which may be in addition to or instead of the second step 603, the first step 601 of controlling the temperature comprises heating at least a part of the NOx control component 10 by means of the heat transfer medium 30, 30'.

In a third alternative first step 605a1, the third step 605 of heating comprises directing a flow 40 of heat transfer medium 30 over an outer surface portion of the NOx control component 10. Therefore, when the heat transfer medium 30 flows over the outer surface portion 14, the heat transfer medium 30 can release heat to the NOx control member 10.

In a third alternative second step 605a2, the fluid in the heating line is heated by a burner and the heated fluid is used to form at least a portion of the heat transfer medium 30.

In a fourth alternative first step 605b1, the third step 605 of heating comprises receiving heat released to the NOx control component 10 by a phase change of the heat transfer medium 30'. This step 605b1 is generally preceded by the step of selecting a heat transfer medium that is selected to be a phase-change heat transfer medium that is suitable for the desired temperature variations of the NOx control component 10.

In a fourth optional step 607, the NOx control component 10 is heated by adding heat to the exhaust gas 3 upstream of the NOx control component 10. This may be done, for example, by using a combustor or turbine bypass passage.

It should be understood that the NOx control component 10 in the EATS 1, 1' described herein may be, for example, a Diesel Oxidation Catalyst (DOC) component or a NOx adsorber, such as a Passive NOx Adsorber (PNA), Lean NOx Trap (LNT), or other type of NOx adsorber.

Furthermore, it should be noted that the EATS 1,1 'shown in fig. 1 may correspond to any of the EATS 1, 1' described in fig. 2 and 5.

It is to be understood that the invention is not limited to the embodiments described above and shown in the drawings; rather, those skilled in the art will recognize that many modifications and variations are possible within the scope of the present invention.

Claims

1. A method for controlling the temperature of a NOx control component (10) in an exhaust gas aftertreatment system (1, 1') of an internal combustion engine, the NOx control component having an inner surface portion (12) defining an inner component space (20) through which exhaust gas (3) is arranged to flow for NOx control, and an outer surface portion (14) facing away from the inner component space, the method comprising:

controlling a temperature of at least a portion of the NOx control component via a heat transfer medium disposed outside the outer surface portion,

wherein the step of controlling the temperature comprises: cooling at least a portion of the NOx control component by the heat transfer medium, characterized by the further steps of: -draining a sub-portion (5) of the exhaust gas downstream of the NOx control component and using the sub-portion to form at least a part of the heat transfer medium.

2. The method of claim 1, wherein the step of controlling the temperature comprises: directing a flow of the heat transfer medium to flow over the outer surface portion of the NOx control component.

3. The method according to claim 1, characterized by the further step of: forming at least a portion of the heat transfer medium using an external cooling gas.

4. A method according to claim 3, wherein the external cooling gas is ambient air (40).

5. The method of any of claims 1-2, wherein controlling the temperature comprises: heating at least a portion of the NOx control component via the heat transfer medium.

6. The method according to claim 5, characterized by the further step of: heating a fluid in a heating line (72) by a burner (70) and using the heated fluid to form at least a portion of the heat transfer medium.

7. The method of claim 1, wherein the step of controlling the temperature comprises: receiving heat from or releasing heat to the NOx control component through a phase change of the heat transfer medium.

8. The method of claim 1, wherein the NOx control component is a diesel oxidation catalyst, a DOC component, or a NOx adsorber.

9. The method of claim 8, wherein the NOx adsorber is a passive NOx adsorber, PNA, lean NOx trap, or LNT.

10. An exhaust gas aftertreatment system (1, 1') comprising a NOx control component (10) having an inner surface portion (12) defining an inner component space (20) through which exhaust gas (3) is arranged to flow for NOx control and having an outer surface portion (14) facing away from the inner component space, characterized in that the exhaust gas aftertreatment system further comprises a heat transfer device arranged to at least partially surround the NOx control component, the heat transfer device being configured to contain a heat transfer medium for controlling a temperature of the NOx control component by receiving heat from or releasing heat to the outer surface portion of the NOx control component,

wherein the heat transfer device comprises an inlet (52) for receiving the heat transfer medium and an outlet (54) for discharging the heat transfer medium, thereby allowing the heat transfer medium to flow through the heat transfer device, and wherein the heat transfer device is configured to direct a flow of the heat transfer medium to flow over the outer surface portion so as to receive heat from or release heat to the NOx control component,

the exhaust gas aftertreatment system (1, 1') further comprises: a selective catalytic reduction unit (60) disposed downstream of the NOx control component; and a cooling bypass channel (5') configured to drain a sub-portion (5) of the exhaust gas downstream of the catalytic reduction unit, and wherein the heat transfer medium at least partially comprises the sub-portion to receive heat from the NOx control component.

11. The exhaust aftertreatment system of claim 10, further comprising an air inlet (40') configured to receive ambient air (40), and wherein the heat transfer medium at least partially includes the received ambient air to receive heat from the NOx control component.

12. The exhaust aftertreatment system of claim 10, further comprising a burner (70) configured to heat fluid in a heating line (72), and wherein the heat transfer medium at least partially includes the heated fluid to release heat to the NOx control component.

13. The exhaust aftertreatment system of claim 10, wherein the heat transfer medium is selected to be a phase-change heat transfer medium, and wherein the heat transfer device includes an expansion vessel (56') configured to: the expansion vessel compensates for a volume change of the phase-change heat transfer medium when the phase-change heat transfer medium undergoes a phase change upon receiving or releasing heat from or to the NOx control component.

14. The exhaust aftertreatment system of claim 10, wherein the NOx control component is a diesel oxidation catalyst, a DOC component, or a NOx adsorber.

15. The exhaust aftertreatment system of claim 14, wherein the NOx adsorber is a passive NOx adsorber, PNA, lean NOx trap, or LNT.

16. A vehicle comprising an exhaust aftertreatment system according to any one of claims 10 to 15.

17. A computer readable medium carrying a computer program comprising program code means for performing the steps of the method as claimed in any one of claims 1-9 when said computer program is run on a computer.